One of the conventional structures of an SD card consists of a card shell and a memory module, such as described in U.S. Pat. No. 6,381,143.
U.S. Pat. No. 6,399,906 describes an IC card connector for electronic devices. The connector has a receptacle portion to receive an IC card, and has a built in switch that can detect the card write protection switch setting. The switch has at least two positions; a position for allowing the host to read and write normally and another position for write protection. When the switch is in the write protection position, the host can read data from the card but cannot write or erase data. The switch is a plastic piece that is inserted inside the groove on the side of the card and can slide in the groove. The switch does not make any contact with the electrical circuit on the card.
The card outside shell is typically made from two half shells and is welded together by applying ultrasonic waves to the two halves jointing locations and melting the joints. Typically the shell is made from plastic material, made by an injection molding process with the thickness in each half approximately 0.3 mm.
The shell has an edge protruding away from the shell surface along the outer periphery of the shell. On top of the edge there is pre-arranged intermittent protruding ridge and the shape is triangular in cross-section. These ridges are to be melted during ultrasonic welding.
Assembly typically consists of first inserting the lower cover into the ultrasonic machine lower die, then inserting the module on top of the lower cover, then inserting the switch and then inserting the top cover. Next, the ultrasonic machine upper die is lowered to press the upper cover against the lower cover, with the ridges are resting against the other cover peripheral edge. Next, the ultrasonic wave is turned on. Since the lower cover is being held steady by the lower die and is not moving, and the upper cover is vibrated by the ultrasonic wave, the friction between the covers generates heat to melt the protruding ridges and weld the two covers together.
There are several problems associated with the above-described manufacturing process. For example, since the ridges on the card case are small, even after the ridge is melted, it becomes a thin line of plastic holding the two halves together. The thin welding line has limited strength, and can be pulled apart.
In addition, the card case and module are two separate units, but one unit does not strengthen the other. Therefore, it is not as strong as if the two units were interfused, and is easier to be deformed due to bending or twisting when in use.
A further problem with the ultrasonic welding process is that it is labor intensive. As mentioned above regarding the card assembling process, because of the complex shapes of the covers and modules, the loading of covers, module and switch are usually handled by human hands. Also, the alignment of these parts is critical. During the ultrasonic head lowering process and making contact with the covers, one has to watch the alignment of the parts. So, it can be seen that the assembling process is difficult to be automated and implemented into “on line” production.
Another aspect of ultrasonic welding is that the welding quality has to be assured. The ultrasonic wave power has to be enough to melt the joints evenly around the peripheral edges, but overpowering may damage the electrical components on the module.
The present invention addresses these problems by utilizing plastic molding techniques of injecting plastic material to form the card outer body. As the card body plastic is bonded to the module, the plastic body and module become one unit. Also, the manufacturing process can be more automated.
The referenced patents reflect the current state of the art of which the present inventor is aware. Reference to, and discussion of, these patents is intended to aid in discharging Applicant's acknowledged duty of candor in disclosing information that may be relevant to the examination of claims to the present invention. However, it is respectfully submitted that none of the above-indicated patents disclose, teach, suggest, show, or otherwise render obvious, either singly or when considered in combination, the invention described and claimed herein.